So if I move to CA now with a pistol and Magazines with more than a 10 round capacity, can I keep them? Thanks ahead of time.

You may not legally bring them into CA as complete magazines.

You may, under current law, take those mags apart and bring them in as 'parts kits', but may not legally re-assemble them inside CA. Again, under current law, you may also take those parts kits and block their capacity to 10 or fewer rounds; at that point you may assemble them in their new limited capacity and legally use them.